The International Business Machine Corporation (IBM) 3270 communication protocol supported by the model 3270 terminal is a relatively old system. The “3270” class of computer terminal has been manufactured and sold by IBM since 1972. The term “3270” is also utilized to denote a type of protocol utilized by 3270 compatible terminals to communicate with a mainframe computer. The 3270 terminal is generally a “smart display device” that has at least one microprocessor and a 3270 terminal can receive and display data and communicate utilizing blocks or packets of data.
The 3270 terminal can be referred to as a secondary logical unit (SLU) where the mainframe can be referred to as a primary logical unit or (PLU). Unlike common mainframe terminal protocols, functionally the 3270 protocol minimizes the number of input/output interrupts during operation by accepting large blocks of data in a 3270 data stream. Accordingly, the 3270 protocol/system utilizes a high speed proprietary communications interface. Thus, although a 3270 is a relatively old system/protocol/architecture it is still functional and currently in use in many forms. A 3270 system still provides a robust and secure communication and computing environment.
IBM stopped manufacturing the 3270 years ago, however many vendors provide emulation software that can be loaded onto a personal computer such that a personal computer can operate as a 3270 terminal. Thus, the IBM 3270 protocol is still commonly used via emulation on a personal computer and such a configuration allows users to access mainframe-based applications. Some attempts at modernizing 3270 terminals include the use of a technique known as “screen scraping.” In such a technique a non 3270 system can receive and capture 3270 screen data and can transfer the data into a modern display format such as a Microsoft Windows™ format. Such a process is less than perfect because to screen scrape the computer must leave the secure 3270 communication mode making the mainframe and the 3270 compatible terminal susceptible to hacking and other corruption. Today, many businesses still find the 3270 system to be very productive and efficient and often cannot justify spending the resources to replace the 3270 system with more modern/expensive systems with compatible security.
Current mainframe computers still provide the fastest execution speeds in a secure environment in a centralized manner and thus, are robust and provide the required control and security for many industries. For these reasons, and many more there continues to be a place for mainframe computing in the machine hierarchy with multiple remote user terminals. In contrast, efforts to improve the user-to-mainframe interface, particularly for legacy mainframe computers seem to be lacking. Much of the data entry and programming work on mainframes today is accomplished with microprocessor based terminals or equipment that is designed to emulate the characteristics of the mainframe and terminals that were utilized in the 1960's and 1970's.
The 3270 protocol supports communications for the IBM series of mainframe computers that can operate on an IBM 360 mainframe instruction set. In the typical network deployment data can be exchanged between a host computer or PLU and a client application or a compatible terminal as defined in IBM's System Network Architecture (hereinafter, “SNA”) and a user terminal or terminal server or the SLU. The 3270 protocol defines sending and receiving data in blocks and the terminals can request retransmission of data. The 3270 terminal has been so long the established standard that many lines of application code have been written that depend on the exact characteristic behavior of this terminal model. The 3270 terminal has been so widely emulated by third parties that the 3270 data formatted stream on which it operates has become an industry standard. However, the basic 3270 terminal has fallen out of favor in state-of-the-art computing because of its limited capabilities. For example, graphical user interfaces (GUI)s are very popular in today's computing environment, yet the 3270 terminal generally does not support such an “advanced” format.
For example, a popular GUI utilized by many, is provided by Web browser applications or a “browser.” A browser application can denote software that can be utilized to receive and process web compatible languages such as a hypertext markup language (HTML). Browsers are generally well accepted by users and provide excellent flexibility as to what functions they provide and what they can accomplish for a user. For example, a browser can allow a user to interact with displayed text, images, videos, music and other data. Browsers allow a user to quickly and easily access information by pointing and clicking on icons and selecting links or traversing links using a pointing device such as a mouse. Browsers can also format information/data or commands into an HTML format such that many different GUIs can display the data. The GUI can provide an improved appearance of a data or Web page as compared to traditional terminals. Although browsers are typically used to access the World Wide Web, they can also be used to access information provided by mainframes in private networks or can be effectively utilize to access content in file systems for example banking records.
The most commonly used HTTP is HTTP/1.1, which is fully defined in request for comments 2616. Most browsers natively support a variety of formats in addition to HTML, such as the JPEG, PNG, and GIF image formats, and most browsers can be extended to support more data formats through the use of browser compatible plug-ins. These formats can be generally referred to as “web compatible” formats. The combination of HTTP type content and URL protocol specifications allow Web page designers to embed images, animations, video, sound, and streaming media into a Web page, enhancing a user's experience. Some of the more popular browsers include additional components to support “Usernet” news, IRC (Internet relay chat), and e-mail capabilities. Protocols supported may include NNTP (network news transfer protocol), SMTP (simple mail transfer protocol), IMAP (Internet message access protocol), and POP (post office protocol). These browsers are often referred to as Internet suites or application suites rather than merely Web browsers, however all of these protocols are considered “Web compatible.”
Generally, there has been a lack of significant improvement in mainframe terminal technology over the last few decades. Accordingly, what is needed is a different kind of SLU processing that uses the robust network and security already established by the 3270 while modernizing the user interface.